Nitrated fabric for lace making and method for making same



UNITED STATES PATENT OFFICE NITRATED FABRIC FOR LACE MAKING AND METHOD FOR MAKING Joseph Datlow, Brooklyn, N. Y.

NoDrawing. Application November 22, 1940, Serial No. 366,788

3 Claims. (Cl. "8-120) This invention relates to nitrated cellulose fabcompletely soluble in a caustic oralkaline solurics which are adapted'to' be used as a backing tion, may be provided by nitrating such fabric or ground fabric in the process of making lace in abath containinga major. percentage of phosand like articles, and to a method and means for phoric acid. v manufacturing such nltrated fabrics. Prior to nitration the fabric may be dried for Heretofore such backing or ground material about five minutes at about 120 F. in an oven. has been prepared by nitratingcheap cotton fabin order to remove substantially all the moisture rics, such ascheese cloth, in sulphuric-nitric acid therefrom. I then submerge the fabric v in a nibaths to render the same completely soluble in trating bath prepared in accordance with my caustic soda. Such nitrated fabrics have had. a 10 invention. Said bath shouldc'omprise'a mixture comparatively high nitrogen content, varying of nitric andphosphoric acids wherein the phosfrom about 8% to about 12%, since with a niphoric acid consists of a major percentage by trogen content lower than 8% the fabric could volume. I have found that baths in which the not be completely dissolved in caustic soda so as percentage by volume of nitric acid ranges from to free the lace therefrom. On the other hand 5 about 5% to 30% and that of the-phosphoric acid the large percentage of nitrogen has rendered from 70% to 95% will give satisfactory results. the backing material highly inflammable and If desired, to reduce cost, a small percentage of otherwise hazardous to use. the phosphoric acid may be replaced by sul- It has been proposed to load the fabric in any phuric acid in amounts varying from about 0.5%

- of several various manners with a fire-proofing to 8% of the total bath composition by volume.

material. Such procedure and the resulting fab The time that the fabric is left submerged in ric, however, are subject to several drawbacks: the nitrating bath is inversely proportional to the the method involves the use of relatively extemperature at which the bath is maintained. pensive substances and therefore renders the ni- For example, at temperatures around 40 F. a-

trated fire-proofed fabric relatively costly; a fabperiod of submersion of about thirty-sixhours is rlc flre-proofed in t is manner is rough and stiff required. At 60 F. eight to twelve hours would and thus extremel difiicultto stitch upon; the be sufiicient. From about 100 F. to 120 F. the treated fabric is appreciably more hygroscopic submersion period is about an hour, while at than untreated cotton fabrics and the increased temperatures at or slightly over 120 F. one-half absorption of moisture by such fire-proofed fabhour will suflice.

ric has resulted in causing the needles of the em- After the fabric is removed from the nitratbroidery machine and other parts of such machining bath it is washed ,out with water to remove cry to rust. most of the acid. The fabric is then washed in a Accordingly, it is the principal object of my weak soltuion of an alkaline substance, such as invention to overcome these and other disadvansodium carbonate or tri-sodium phosphate, to', tages and to provide a novel method and means neutralize the remaining acid, and finally the rewhereby a highly improved backing or ground sidual alkaline substance is washed out with wawill be obtained at a relatively low cost. ter.

Another object of my invention is to provide Byway of illustration and without limiting mya nitrated fabric of the character described which self to this particular form of my invention, the shall to a high degree be less inflammable than following illustrates a bath composition which the cellulose fabric from which it was prepared, will give satisfactory results: which shall retain its original tensile strength, Parts by which shall have a percentage by weight of nivolume trogen considerably below that presently em- Nlmc E 3 97% 25 ployed, and yet completely dissolve in relatively Phosphor? a1d"cncentrat1n about 75 low concentrations of caustic soda or in solutions A fabri prepared by submersion in the above of an even w a r al al p d bath, at a temperature of about 100 F. for one o r jects ofmy invention will in part be r hour, and subsequently washed out in the manner obvious and in part hereinafter pointed out. above described, will have about'0.5% by weight Describing my invention in general terms, I of nitrogen. This percentage may be varied, have found that a strong non-inflammable and without departing from the spirit of my invenalkaline-soluble cellulose fabric containing a pertlon, between about 0.4% and 1% by altering the centage by weight of nitrogen considerably below K3 nitrating bath composition within the ranges the minimum heretofore required to render same above stated and by manipulating the temperature and tilhe controls of the submergence period.

A nitrated fabric prepared in the manner above described is soft and can hardly be distinguished by touch from un-nitrated cloth. Also, the treated fabric will have the same or a slightly greater tensile strength than the original cloth and about the same degree of hygroscopicity. The treated fabric is non-inflammable and upon the application of high temperatures will merely char. The nitrated fabric can be completely dissolved in relatively low concentrations of caustic soda. Thus, for example, a fabric containing 0.5% of nitrogen can be completely dissolved in caustic soda solution of as low as 3 Baum. This should be contrasted with the extremely strong caustic concentrations heretofore employed where high degrees of nitration were obtained in a nitrating bath principally comprising nitric, and sulphuric acids.

I may also carry out the step of dissolving my improved nitrated fabric in solutions having a lower pH value than caustic soda, as for example aqueous solutions of sodium carbonate.

It will thus be seen that there is provided a product and a method and means for manufacturing the same in which the several objects of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiments above set forth, it is to be understood that all matter herein set forth is to be interpreted as I illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An alkaline-soluble, non-inflammable, nitrated, cellulose backing fabric for use in making lace and like articles, said fabric containing from about 0.4% to 1% by weight of nitrogen, said fabric having been rendered alkaline-soluble and non-inflammable by nitration in nitric acid in the presence of phosphoric acid.

2. An alkaline-soluble, non-inflammable, nitrated, cellulose backing fabric for use in making lace and like articles, said fabric containing about 0.5% by. weight of nitrogen, said fabric having been rendered alkaline-soluble and noninflarnmable by nitration in nitric acid in the presence of phosphoric acid.

3. In the process of nitrating and fire-proofing cellulose fabrics to provide a backing fabric for use in making lace and like articles that improvement which comprises the step of imparting from about 0.4% to 1% by weight of nitrogen to the fabric by treatment with nitric acid in the presence of phosphoric acid.

JOSEPH DATLOW. 

